Are reliability, reproducibility and validity the correct terms to assess the correctness of dietary studies?

Nutritional studies often use the terms reliability, reproducibility and validity to indicate the correctness of the study. These terms do not appear to have a universal meaning to all researchers. The components of a dietary study are the input, the data collection instrument and the compiled data. Frequently the data collection questionnaire/tool/instrument is tested for reliability, reproducibility or validity. The data collection questionnaire/tool/instrument is simply a structure, a vehicle for gathering data. An argument is presented that demonstrates the reasons that such a structure cannot be tested for reliability, reproducibility or validity. The logical approach to the use of the terms reliability, reproducibility and validity is presented. Reliability refers to the input component of the study, reproducibility may or may not lead to strengthening the study and validity refers to the truthfulness of the database generated. Validity must be derived from reliable and reproducible data.